CHICAGO — A hypofractionated radiotherapy regimen administered in 20 fractions over 4 weeks was noninferior to conventional radiotherapy given as 39 fractions over 8 weeks without compromising safety in patients with localized prostate cancer, findings presented at the 2016 American Society of Clinical Oncology (ASCO) Annual Meeting indicate.1
“External beam radiotherapy is commonly used to treated intermediate-risk prostate cancer,” said lead investigator Charles Catton, MD, professor of radiation oncology at the University of Toronto in Canada. “A typical radiotherapy course is between 7.5 and 8.5 weeks.”
The α-β ratio, which describes the dose-response of tumors and normal tissues to fractionated radiotherapy, is low for prostate cancer. Therefore, researchers hypothesized that hypofractionation radiotherapy may be more efficacious in prostate cancer.
For the PROFIT trial, researchers enrolled 1206 men with intermediate-risk prostate cancer (T1-2, Gleason score 6, and PSA 10 ng/mL to 20 ng/mL or T2b-c, Gleason score 6, and PSA <20 ng/mL, or T1-2, Gleason 7, and PSA <20 ng/mL) from 27 sites in Canada, Australia, and France. Patients were randomly assigned 1:1 to 78 Gy radiotherapy in 39 fractions over 8 weeks (conventional radiotherapy) or 60 Gy radiotherapy in 20 fractions over 4 weeks (hypofractionated radiotherapy), without hormone therapy.
At a median follow-up of 6.0 years, there were 166 biochemical-clinical failure events in the hypofractionated group and 170 in the standard group, the investigators found. The 5-year biochemical-clinical failure rate in both arms was 21% (HR, 0.99; 90% CI, 0.83-1.32; P=.0044 for noninferiority). In addition, there were 76 deaths in the short-course arm vs 78 in the standard-course arm.
“There was no significant difference in median overall survival between the 2 arms,” Dr Catton noted.
In regard to safety, grade 3 or worse gastrointestinal and genitourinary toxicities during the acute period were comparable between the 2 treatment groups; however, there was a trend toward a lower incidence of late toxicity with hypofractionated radiotherapy.
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Further, quality of life over 4 years was similar between the 2 groups.
“The shorter radiotherapy regimen is noninferior to the standard radiotherapy for disease control,” Dr Catton concluded. “Based on patient convenience and cost, the shorter radiotherapy regimen should be considered as a new standard for intermediate-risk prostate cancer.”
- Catton CN, Lukka H, Julian JA, et al. A randomized trial of a shorter radiation fractionation schedule for the treatment of localized prostate cancer. J Clin Oncol. 2016; 34 (suppl; abstr 5003).